In earlier work it was shown that the polyamines, putrescine, spermidine, and spermine, stimulated the phosphorylation of phenol-soluble acidic nuclear proteins (PSANPs) as much as 30-fold above controls in intact, isolated nuclei and nucleoli from Physarum polycephalum. Two proteins among the bulk PSANPs, with molecular weights of 52,000 and 70,000 g/mole, were found to be phosphorylated in the presence of the polyamines to the extraordinary levels of 8 and 30 moles of phosphate per mole of polypeptide, respectively. Both proteins have been shown to be major components of ribosomal deoxyribonucleoprotein (rDNP) chromatin-like minichromosomes that are isolable from nucleoli of Physarum. This rDNP is also isolable as a transcriptionally active complex containing alpha-amanitin sensitive RNA polymerase I. It exclusively transcribes ribosomal genes which reside on a small 38 times 10 to the 6 power dalton, palindromic DNA. The proposed work seeks to determine the role(s) of the 52,000 and 70,000 MW nonhistone proteins in the structure and function of this rDNP complex. Projects are also described which seek to establish that the polyamines and cyclic AMP are elements of a mutual regulatory loop in nuclei. In this loop, the polyamines modulate the activity of polyamine-inhibitable nuclear adenylate cyclase, and cyclic AMP modulates polyamine levels through cyclic AMP-dependent induction of ornithine decarboxylase, the rate limiting catalyst in polyamine biosynthesis. Lastly, the enzyme diphosphoglucose (UDPG) pyrophosphorylase has been purified from vegetative plasmodia. Antibodies directed against this enzyme will be used (1) to establish the homology between isolable isozymes from Physarum; (2) to determine rates of synthesis and degradation of UDPG pyrophosphorylase during differentiation (spherulation) of Physarum, and (3) to determine whether this plasmodial enzyme exists in other differentiated forms of Physarum.